Process for separating indium from contaminants



Aug! 2,1949. y J. L. HART 477,79

PROCESS FOR SEPARA'TING INDIUM FROM CONTAMINANTS Filed June 28. 1947 m EH SM/175K mfr/6375 O 0 f7 F/L TE R 77' ORNE Y Patented ug. 2, 1949 ENT PROCESS FOR SEPARATING INDIUM FROM CONTAMINANTS .lames L. Hart, Bartlesville, Okla., assignor to American Smelting and Relining Company, New York, N. Y., a corporation of New Jersey Application June 28, 1947, Serial No. 757,764

4 Claims. l

This invention relates to the art of recovering indium from indium-bearing materials and, more particularly, to the purication of indium solutions with respect to such contaminants as copper, arsenic, selenium, tellurium, etc.

Iridium, like cadmium, commonly occurs as a minor constituent of certain zinciferous ores. When ysuch ores are roasted, the indium passes into the fume along with cadmium, arsenic, lead and other constituents. In the usual practice of treating such fume to recover the cadmium, there remains a so-called lead sulphate residue normally comprising lead, arsenic and cadmium as major components together with such minor components as Zinc, selenium, tellurium, iron, copper, etc. and the indium. The present invention aiords decided advantages in recovering 2 be seen from a reading thereof, the invention enables one to obtain Va practically complete recovery of indium from the starting material.

In this instance, the original material consisting of 3,000 lbs. Wet lead sulphate residues equivalent to 2330 lbs. on a dry basis analyzing 0.012 oz./T. Au and 4.0 ca /T. Ag and other constituents as shown in the accompanying table, was treated with 1060 lbs. 98% II2S04 and 100 cu. it. H2O. The mass was thoroughly agitated and ltered thereby yielding 2170 lbs. Wet lter cake equivalent to 1800 lbs. dry cake A analyzing 0.015 oz./T. Au and 5.2 oz./T. Ag and other constituents as set forth in the table below. The filtrate B amounted to 100Acu. it. and contained the indium and amounts of other constituents shown in the table on a gram/liter basis.

Table of Analyses 1 Se Material Pb Cu Cd Zn As and Fe In Original Material 41. 7 0. l 5. 87 3. 5 6. 8 1. 5 1.0 2. 3 Filter Cake A 54. 0 .O9 1.26 0. 3 2.0 0.5 0.05 0.05 Filtrate B None 0. l 18. 2 12.1 19. 5 4. 2 3.5 8. 4 Filter Cake C". None 0.5 59.0 7. 2 0.1 Filter Cake D None 16 1.01 3.41 0. 2 1. 9 30. 5 Indium Cake X.. None None None 0.1 Trace 0.5 43.0

1 Expressed in percent (dry basis), except filtrate B which is gm ./1.

indium from such residues, and is generally applicable to the treatment of indium-bearing solutions from other sources which present a similar purification problem.

The drawing accompanying this specification and forming a part thereof is a flow sheet illustrating the process of the invention.

Briefly, the invention contemplates solubilizing the indium content of indium-bearing material by reaction with a suitable acid solution, and purifying the solution, particularly with respect to such contaminants as copper, arsenic, selenium and tellurium, by incorporating therein sodium hyposulphite (NazS2O4)-commonly sold in the trade under the name sodium hydrosulphite and filtering. The indium is then ordinarily precipitated from the solution, preferably as indium phosphate or indium hydroxide, in which form it is readily amenable to conversion to indium metal. Ii desired or necessary, the indium precipitate may be redissolved, the hyposulphite purication step repeated and a second indium precipitate made, prior to converting to indium metal,

The speciiic example which follows is given to illustrate the process of the invention and, as will To the indium-bearing iiltrate B, there was added 350 lbs. sodium hyposulphite whereby (following agitation and ltration) there Was obtained lbs. of wet filter cake equivalent to 148 lbs. dry cake C having the analysis shown in the table. The ltrate from this operation Was diluted to 200 cu. ft. and 10% monosodium phosphate solution in slight stoichiometrical excess of the indium present, together with suiiicient 50% NaOH solution to bring the pH of the i'lltrate to approximately 3.2, was added. Upon ltering, there was obtained 432 lbs. of Wet lter cake equivalent to 173 lbs. dry cake D having 'the analysis shown in the table.

The filter cake D was redissolved with 254 lbs. 98% H2SO4+100 cu. ft. H2O', 12 lbs. of sodium hyposulphite added, and filtered. The wet cake amounted to 1.2 lbs. equivalent to 0.7 1b. on a dry basis containing 3.9% As and 50.2% Se and Te. The filtrate was diluted to 200 cu. it. and the indium again precipitated using 3 cu. ft. of 10% monoscdium phosphate solution with suicient NaOI-I to bring the pH to 3.2. Upon filtering there was obtained 488 lbs. of Wet iilter cake equivalent on a dry basis to 123 lbs. indium From the foregoing description, it Will be apparent that the present invention provides a .simple procedure for separating indium from its common contaminants such as those hereinbefore mentioned. While other factors may be involved, the beneficial results are believed to be largely attributable to a rather complete reduction of not only arsenic and iron by the sodium hyposulphite but of copper and selenium and teilurium as well.

While certain novel features of the invention 'L have been pointed out Vand disclosed, it will be understood that various omissions, substitutions and changes may be made by those skilled in the art Within the Y'scope 'of the invention as defined by the following claims.

What is claimed is: Y

1. In a process for recovering indium from indium-bearing material by solubilizing the indium `in an acid solution, purifying the resulting solution, and subsequently recovering indium by precipitation from -theipuried solution, the improvement in purification which consists in reacting the acid solution with sodium hyposulphite (Na2S2O4-) thereby rendering such contaminants as copper, arsenic, selenium and tellurium amenable to removal by ltration.

2. The method of purifying an acid solution of indium with respect to such contaminants as copper, arsenic, selenium and tellurium which comprises incorporating sodium hyposulphite (NazSzOi) in the solution, and filtering.

3. The process for treating indium-bearing material which comprises reacting same with acid to solubilize the indium, i'iltering,'incorpo rating sodium hyposulphite (Na2S2O4) in the first ltrate, again filtering, and precipitating indium from the second filtrate.

4. The method of purifying indium in acid solution which comprises reacting same with sodium hyposulphite (NazSzOr), filtering, precipitating indium from the filtrate, redissolving the indium precipitate in acid solution, reacting the Vlatter With a further quantity of sodium hyposulphite, and filtering. Y

- JAMES L. HART.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,241,438 Zischkau et al. May 13, 1941 ascetic Doran et al. --.7---- sept. 11, 1945 OTHER REFERENCES l Mellor, A Comprehensive Treatise on Inorganic and Theoretical Chemistry, Longmans, Green & Co., N. Y., 1937, vol. 5, p. 389. 

